AskDefine | Define irradiation

Dictionary Definition



1 the condition of being exposed to radiation
2 a column of light (as from a beacon) [syn: beam, beam of light, light beam, ray, ray of light, shaft, shaft of light]
3 (physiology) the spread of sensory neural impulses in the cortex
4 the apparent enlargement of a bright object when viewed against a dark background
5 (Pavolvian conditioning) the elicitation of a conditioned response by stimulation similar but not identical to the original stimulus
6 (medicine) the treatment of disease (especially cancer) by exposure to radiation from a radioactive substance [syn: radiotherapy, radiation therapy, radiation, actinotherapy]

User Contributed Dictionary




  1. act of irradiating, or state of being irradiated.
  2. illumination; irradiance; brilliancy.
  3. fig.: mental light or illumination.
  4. the apparent enlargement of a bright object seen upon a dark ground, due to the fact that the portions of the retina around the image are stimulated by the intense light; as when a dark spot on a white ground appears smaller, or a white spot on a dark ground larger, than it really is, esp. when a little out of focus.
  5. a process of sterilisation whereby radiation is passed through a bag containing food, utensils, etc., to sterilise the contents.


Extensive Definition

Irradiation is the process by which an item is exposed to radiation. The exposure can be intentional, sometimes to serve a specific purpose, or it can be accidental. In common usage the term refers specifically to ionizing radiation, and to a level of radiation that will serve that specific purpose, rather than radiation exposure to normal levels of background radiation or abnormal levels of radiation due to accidental exposure. This term also applies to 'non-ionizing radiation as microwaves or to low frequency (50/60 Hz power supply), high frequency (as cellular phones, radio and TV transmissions).



If administered at appropriate levels, all of these forms of radiation can be used to sterilize objects, a technique used in the production of medical instruments and disposables, such as syringes as well as in the disinfestation and sterilization of food. Small doses of ionizing radiation (electron beam processing, X-rays and gamma rays) may be used to kill bacteria in food, or other organic material, including blood. Irradiation also includes (by the principle) microwave heating.


It is also used in cancer therapy.

Industrial chemistry

Irradiation can furthermore be used in cross-linking of plastics or to improve material qualities of semi-precious stones. Due to its efficiency, electron beam processing is often used in the irradiation treatment of polymer-based products to improve the mechanical, thermal, and chemical properties, and often adding unique properties. Cross-linked polyethylene pipe (PEX), high-temperature products such as tubing and gaskets, wire and cable jacket curing, curing of composite materials, and crosslinking of tires are a few examples. Irradiation is also employed to prevent sprouting of certain cereals, onions, potatoes and garlic.


During the 2001 anthrax attacks, the US Postal Service irradiated mail to protect members of the US government and other possible targets. This can be of some concern to people, including artists; according to the ART in Embassies programme "incoming mail is irradiated, and the process destroys slides, transparencies and disks."


See also

irradiation in Arabic: تعرض للإشعاع
irradiation in German: Bestrahlung
irradiation in French: Irradiation
irradiation in Ukrainian: Опромінення

Synonyms, Antonyms and Related Words

X-ray dosimetry, X-ray therapy, anhydration, arc lighting, black and white, blast-freezing, bottling, brining, canning, chiaroscuro, cobalt therapy, contrast, corning, curietherapy, curing, decorative lighting, dehydration, desiccation, direct lighting, dry-curing, drying, electric lighting, emanation, embalming, enlightenment, evaporation, festoon lighting, floodlighting, fluorescent lighting, freeze-drying, freezing, fuming, gaslighting, glow lighting, highlight, highlights, illumination, incandescent lighting, indirect lighting, interstitial irradiation therapy, irradiance, irradiancy, irradiation therapy, isotope therapy, jerking, light, light and shade, light source, lighting, luminous energy, marination, mummification, overhead lighting, photosensitivity, pickling, potting, quick-freezing, radiance, radiancy, radiant energy, radiation, radiation therapy, radiotherapeutics, radiotherapy, radium therapy, radiumization, ray therapy, refrigeration, roentgen ray therapy, roentgenization, roentgenometry, roentgenotherapy, roentgentherapy, salting, seasoning, sidelight, smoking, spot lighting, stage lighting, strip lighting, stuffing, taxidermy, tinning, tonality, visible radiation
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